We use git-flow branching model.
All new feature development and bug fixes occurs in DEV branch. This is our main development branch where all changes planned for the next release are placed. We accept direct commits to this branch when it comes to small changes.
If you would like to contribute a new feature or work on something non-trivial, you should create a feature branch. Once your work is complete, the changes can be merged into DEV branch where they will wait for the next release.
We use hotfix branches for patches of the latest release. Hotfix branches are merged both into the master and development branches.
Before you start working on introducing a new library, please make sure that the license of said library is fully compatible with GNU GPL V3. Credit to original authors of said libraries should be given in the about page.